H.264/AVC, one of standard specifications for image encoding scheme, applies a deblocking filter to a block boundary in units of blocks each containing 4×4 pixels, for example, in order to prevent image quality degradation due to block distortion while an image is encoded. The deblocking filter requires a large amount of processing and may account for 50% of the entire processing amount in image decoding, for example.
The standards work for High Efficiency Video Coding (HEVC), a next-generation image encoding system, proposes application of the deblocking filter in units of blocks each containing 8×8 pixels or more according to JCTVC-A119 (see Non-Patent Literature 1). The technique proposed in JCTVC-A119 increases the block size as a minimum unit for applying the deblocking filter to perform filtering processes in parallel on block boundaries in the same direction within one macro block.